The Effects of Birth Order on Personality Traits and Feelings of Academic Sibling Rivalry Julia Badger & Peter Reddy

The effects of birth order on personality traits and feelings of academic sibling rivalry Julia Badger & Peter Reddy

Abstract The influence of birth order on personality and sibling rivalry is controversial; little research has been conducted into academic sibling rivalry, and none into the connection with personality traits. This study con- siders the interaction of all three factors. Firstborns (N=22) and lastborns (N=24) completed online personality tests and an Academic Sibling Rivalry Questionnaire. Lastborns were found to experience more academic sibling rivalry: t=2.33, DF=44; p<.05, whereas firstborns are more likely to be conscientious: F(1,44)=3.58; p< .05, and dutiful: F(1,44)=5.39; p<.05. This raises possible implications in domains including education, health and psychotherapy. Further research could be conducted to expand these findings in terms of variables and geographical location.

N THE GALAPAGOS ISLANDS Charles each other for not only survival, but also Darwin (1859) found 13 variations of parental favour. Sibling rivalry can be Ifinch and concluded that these variations described as ‘the jealousy, competition and had emerged as the most suitable for that fighting between brothers and sisters’ (Uni- time and that environment through natural versity of Michigan Health System, 2007. selection. Darwin proposed that the ‘fittest’ pp1) and is common when there is more variations within a species were the most than one sibling in a family (Johnson, 1998). likely to survive and reproduce and therefore Trivers (1974) points out that every child ini- more likely to pass on their genetic traits; the tially sees himself as more important than his ‘survival of the fittest’. Darwin believed that it siblings (twice as valuable) and needs to be was survival of the fittest that resulted in off- taught to share and be kind. spring (sibling) rivalry. Rivalry can certainly There are of course instances in other be found within a plethora of biological con- biological kinds whereby siblings support, texts, for example the first Indian Black Plum rather than fight against each other for the tree ovule releases a ‘death chemical’ to benefit of the species: Trivers (1985) starve and kill other Black Plum ovules described how Taiwanese aphids work (Krishnamurthy, Shaanker & Ganeshaiah, together; the firstborn will become the ‘sol- 1997); the first African Black eagle chick to dier’ and protect the second-born who will hatch pecks the other chick to death (Mock, become the ‘reproductive’ caste. Hamilton Drummond & Stinson, 1990; Mock & Parker, (1964) suggests that altruism may be a result 1998); 25 per cent of Spotted Hyena off- of natural selection by re-focusing on the spring succumb to sibling aggression, increas- genetic rather than the individual level: ing to 50 per cent within same-sex litters interest is in the gene pool if it enables more (Hamilton, 1967). Hamilton (1964; Trivers, individuals to survive (inclusive fitness as 1974) suggests that sibling rivalry is a means opposed to survival of the fittest). of competing for scarce resources – as long as the benefits are greater than twice the cost. Sibling rivalry amongst humans Thus natural selection includes the biological The scale of influence of evolutionary factors disposition of offspring to compete against on human behaviour relative to culture and

Psychology Teaching Review Vol 15 No 1 45 © The British Psychological Society 2009 Julia Badger and Peter Reddy social construction is open to debate; clearly Birth order and personality influences social or environmental factors play a part. Sibling rivalry has been well documented Sulloway (2001; p40) discusses ultimate and with connection to birth order and personal- proximate influences on sibling behaviour: ity, however there are still outstanding con- ultimate causes of behaviour are ‘adaptive troversies (with few consistent findings; tendencies that have evolved by natural Schooler, 1972) over the types of rivalry selection’, and encompass Darwin’s theory investigated. Adler (1927; Leman, 1985) of natural selection and the biological dispo- remarked that birth order is a great contrib- sition to compete for parental focus and utor to why children of the same family, with attention to survive childhood, whereas similar genes, end up with very different per- proximate causes of behaviour are due to sonalities. Adler claimed that the firstborn ‘influences operating during the life- child experiences the ‘only child life’ and is time…biological as well as environmental centre of attention until the second-born factors, which almost always interact with child arrives, which can cause anger and one another’. These influences include vary- frustration. If the situation is handled appro- ing environmental situations that the indi- priately, the firstborn child could develop vidual must react to, to successfully proceed into a responsible, protective person. How- through life and survive natural selection. ever, in extreme cases when the situation is For example, bird migration is an ultimate handled inappropriately, the firstborn can adaptation based on natural selection, how- become neurotic and criminal. Adler char- ever, the immediate triggers for migration – acterises lastborns as ambitious but spoilt: the proximate causes – may include temper- this child is constantly trying to catch-up with ature and length of daylight (Mayr, 1961). or surpass the eldest child but is more likely Therefore, the cause of human sibling to become a neurotic problem child. Sul- rivalry may ultimately be traced back to nat- loway (2001; 1996) claims that firstborns ural selection (Sulloway’s ultimate influ- seek parental approval by taking on the role ence), however, the way in which an of surrogate parent to their sibling (leading individual conducts their rivalry depends on to conscientiousness), whereas laterborns, immediate, or proximate environmental, unable to take on this surrogate role, social and situational factors (Sulloway’s develop new talents and seek new interests proximate influence). and activities within the family in order to Siegler (2007) notes a variety of possible prove that they are worthy of attention (lead- non-biological influences on human sibling ing to openness to experience). Roach rivalry: parental conflict; parental favourites – (1997) replicated Sulloway’s work cross-cul- this can increase the rivalry from the ‘less- turally, among several hundred horticultur- loved’ child and can cause guilt in the ‘loved’ alist Shuar Indians, and found nearly child, and children being encouraged to take identical correlations between birth order on the same hobbies and interests. Lamb and and personality traits. Sulloway (2001) Sutton-Smith (1982) suggest two main types claimed evidence that firstborns are more of sibling rivalry influence: adult-initiated likely to be more conscientious and socially and sibling-generated. Adult-initiated can be dominant, but less agreeable and open to split into two categories: overt and covert. new experiences than laterborns. He also Overt adult-initiated rivalry includes state- notes different competitive strategies ments of comparison between two siblings. between firstborns and laterborns: firstborns Covert comparisons would include subtle – being generally bigger – tend to use more statements without the direct comparison. physical dominance and intimidation, Sibling-generated rivalry attempts to gain whereas laterborns tend to use techniques of parental attention and increase status within whining, humour and social intelligence. the sibling relationship. Zajonc and Mullally (1997; Zajonc, 2001;

46 Psychology Teaching Review Vol 15 No 1 The effects of birth disorder on personality traits and feelings of academic sibling rivalry

Downey, 2001) found that firstborns had a with various sub-questions, asking about more intellectually stimulating environment rivalry at different age ranges and in the than laterborns – the confluence model – three domains. They found that 56 per cent which, influenced the likelihood of differing of individuals had experienced the most sib- personality traits between firstborns and lat- ling rivalry between the ages of 10-15 years, erborns. Zajonc and Mullally commented and the greatest rivalry (38 per cent) had that firstborns experience the ‘tutor effect’ occurred within an academic setting. They (teaching their younger siblings) and their also found that students aged 20-25 rated intelligence benefits from this. Retherford academic sibling rivalry very high: 65 per and Sewell (1991) carried out developmen- cent, with social sibling rivalry at about 30 tal and cross-cultural studies testing this per cent. Between the ages of 20-25, an indi- notion, and found supporting evidence with vidual at college or university has many aca- controlled samples. demic pressures as they strive for Other issues have been noted about gen- achievement and status. When individuals der and age potentially creating, enhancing reach this stage in their education, academic or reducing rivalry. Rimm (2002) suggested rivalry is no longer just about parental that the closer in age two same-sex siblings favour, but also includes competition for are, the more likely it is that there will be respect, status and job prospects: achieving a competition between them and suggests that higher degree is not just seen as a sense of this is because they are expected to like the academic accomplishment, but as a means of same things, act in the same way and achieve securing a higher status career. the same standards. Sulloway (1996; Chu, Yu Although sibling rivalry is seen as a natu- and Tsay, 2004) agreed and stated that ral part of sibling life, if it becomes too greater birth spacing between siblings helps severe it can cause a multitude of problems to reduce sibling rivalry: there is less within the family. Sibling rivalry has been resource competition, and it is more likely found to become so extreme in some fami- that the elder sibling will support the lies that it has led to marital problems, or younger sibling, however Johnson (1998) members of the family having been physi- found no correlation between large birth cally hurt; it has led to a loss of self-esteem, spacing and reduced sibling rivalry. It has with psychological well-being having deterio- been found that female siblings are more rated. Some family members have even had likely to play a supportive rather than a com- to seek advice and help from psychologists, petitive role, compared to males (Green- psychiatrists and other mental health author- halgh, 1985). ities (Sibling Rivalry Disorder, 2007). Sibling rivalry does not necessarily decrease with age Sibling rivalry and real life spacing, number of parents, number of sib- McNerney and Usner (2001) conducted an lings within the family (Johnson, 1998), nor investigation into sibling rivalry across the does it decrease throughout the lifespan lifespan. They investigated the intensity and (McNerney & Usner, 2001), although it may degree of rivalry experienced by 85 college change in focus. By furthering knowledge of students at various stages of their life in three sibling rivalries in a range of situations it may domains: academic, social and physical; be possible to develop interventions to pro- 54/85 described their relationship with their vide coping strategies and support for sibling as competitive. The age ranges (0-25 children suffering with sibling rivalry. in five year increments) were chosen to rep- The aim of this study is to expand on the resent the most ‘important developmental research on sibling rivalry. There are a stages in a person’s life’ (p1). Participants number of variables that could affect sibling completed McNerney and Usner’s sibling rivalry, including gender, birth order, age dif- rivalry survey containing seven questions, ference, parental or environmental influ-

Psychology Teaching Review Vol 15 No 1 47 Julia Badger and Peter Reddy ences, and there are a number of circum- items; each item relates to one of five factors: stances within which rivalry could occur: Extraversion, Agreeableness, Conscientious- home, school, job, social settings and even ness, Neuroticism and Openness to Experi- physical appearance. Acknowledging the dif- ence, all of which have six sub-factors. The ficulties of researching each separate vari- second, paper-based, measure, the Academic able, the previous research undertaken has Sibling Rivalry Questionnaire was devised for been limited and much of the existing this study and comprised of 20 items with research has conflicting evidence. five-point Likert scale responses. Items were This study will focus on academic sibling developed with the aid of focus group rivalry, thought by McNerney and Usner responses. For example: (2001) to be the most prominent form of sibling rivalry between the ages of 10 and 25, M1:‘My sister and my dad had like this and could therefore be seen as the most special connection because they are important form to be studied. This study will both similarly-minded, mathematically- look at whether birth order or certain per- minded and they love all that kind of sonality traits enhance the likelihood of stuff and I used to get really upset about experiencing academic sibling rivalry. stuff like that.’ Three hypotheses were formulated: firstly, there will be a difference in academic E1: ‘My parents still say, well this is what your sibling rivalry scores between lastborn par- sister did, would you not be interested in ticipants and firstborn participants. Sec- doing that? My brother was always ondly, there will be a difference in compared to me.’ Conscientiousness scores, with firstborn participants scoring higher than lastborn par- Participants remarked that parents could ticipants. Finally, there will be a difference have a significant influence on feelings of in Openness to Experience and Agreeable- academic sibling rivalry, therefore items ness scores, with lastborn participants scor- were created to reflect this: ‘I feel my parents ing higher than firstborn participants. The compare my sibling and me’, and ‘I am second and third hypotheses were derived pleased for my sibling if my parents praise from Sulloway’s (1996) research into birth them for their achievements’. order and personality, and were therefore a priori. E2:‘The sibling rivalry in my family came, not necessarily from the parents but Methodology from the teachers at school. They An opportunity sample of forty-six psychol- actually compared us more than our ogy students was recruited through a parents ever did. Stuff was said to my research participation scheme. There were sister before she’d even shown her 22 firstborns (M=19.41 years, range 18-27; character because they knew me and three males and 19 females) and 24 last- they were judging her on my standards.’ borns (M=19.91 years, range 18-25; five males, 19 females). Participants were all Furthermore, some participants felt that native English speakers, and had only one teachers could also contribute to this rivalry, sibling. Participants individually completed therefore items were created in accordance two measures with order of presentation with this: ‘It does not bother me if teachers counterbalanced. Personality was measured compare my sibling and me’ by the IPIP-NEO (International Personality Item Pool: an online representation of the E3: ‘There was always more academic rivalry NEO PI-R; Costa & McCrae, 1992). The five- with my little brother because we’re point Likert scale IPIP-NEO contains 120 more similar: he’s good at things I’m

48 Psychology Teaching Review Vol 15 No 1 The effects of birth disorder on personality traits and feelings of academic sibling rivalry

good at. I’d never help my brother with Results work because he doesn’t do as much When the items for the IPIP-NEO are work as I did.’ scored, a result is given for each of the 5 factors and each of their 6 sub-factors; these are All participants commented about personal a matter of degree, two people can be rated academic feelings towards their siblings, as ‘extraverts’, but one can be more therefore items were created such as ‘I often extraverted than the other. A score of 60, for compare my academic successes against my example, means that your level on that fac- sibling’s successes’, and ‘I feel I deserve bet- tor is estimated to be higher than 60 per cent ter grades than my sibling’. of persons of your age-range and sex (IPIP- A pilot study of 21 participants was con- NEO online). ducted; comments about clarity, ambiguities and structure were accepted and the ques- Birth order and academic sibling rivalry tionnaire was altered. Piloting ensured satis- Preliminary analyses showed that there was a factory test - re-test reliability (r (20)=0.95, difference in levels of academic sibling p<.001) and internal validity (through item rivalry dependent on birth order. Lastborns analysis) was carried out in developing the experienced higher, and less variable, rates final version; ten items were discarded, leav- of academic sibling rivalry (M=60.38; ing twenty highly discriminating items within SD=13.53) compared to firstborns (M=50.18, the questionnaire. SD=16.11), as shown in Figure 1.

Figure 1: Mean academic sibling rivalry questionnaire scores for firstborn and lastborn participants

Psychology Teaching Review Vol 15 No 1 49 Julia Badger and Peter Reddy

The mean difference between conditions tiousness, neuroticism, and openness to was 10.19; the 95 per cent confidence inter- experience. The IV was birth order of the val for the estimated population mean dif- participant. There was no significant differ- ference is between 1.38 and 19.09. T=2.33, ence overall between firstborns and last- DF=44; p<.05. It was concluded that birth borns on the combined DVs: F(5,40)=.75; order affects feelings of academic sibling p=.59. Wilks’ Lambda=.91; partial eta rivalry. squared=.09. A priori comparisons on conscientiousness, openness to experience and Birth order and personality agreeableness enable one-tailed analyses; Preliminary analyses showed there to be a when considered separately, only conscien- main difference between birth order and tiousness reached significance at the .05 conscientiousness, with firstborns exhibiting level: F(1,44)=3.58; p<.05. Firstborns scored higher levels of conscientiousness (M=54.45; higher for conscientiousness compared to SD=7.10) than lastborns (M=38.88; lastborns (see Figure 2). SD=28.64). An independent one-way MANOVA was Birth order and conscientiousness conducted to investigate birth order differ- sub-factors ences in personality factors. The five DVs An independent one-way MANOVA was con- were extraversion, agreeableness, conscien- ducted to investigate birth order differences

Figure 2: Firstborns are more conscientious than lastborns: Scores on the big five personality factors

50 Psychology Teaching Review Vol 15 No 1 The effects of birth disorder on personality traits and feelings of academic sibling rivalry in the six sub-factors of conscientiousness. intelligent than lastborns as they are pro- The six DVs were self-efficacy, orderliness, vided with a more intellectually stimulating dutifulness, achievement-striving, self- disci- environment, which could explain why last- pline, and cautiousness. The IV was birth born siblings would feel more in competi- order of the participant. There was no sig- tion to ‘catch up’. nificant difference overall between firstborns Two hypotheses derived from Sulloway and lastborns on the combined DVs: (1996) were proposed: firstly, a difference in F(6,39)=1.77; p>.05. Wilks’ Lambda=.79; par- Conscientiousness scores, with firstborns tial eta squared=.21. When considering the scoring higher than lastborns was predicted DVs separately, dutifulness was significantly and supported. Secondly, a difference in different between birth orders: F(1,44)=5.39; Openness to Experience and Agreeableness p<.05, with firstborns scoring higher scores, with lastborns scoring higher than (M=59.59) than lastborns (M=42.88). firstborns was predicted but not supported. It is interesting to note that firstborns score Gender and sibling gender differences lower on academic sibling rivalry and higher There was no significant difference between on the Conscientiousness scale. This could males and females on scores of academic sib- be explained by Zajonc and Mullally’s ‘tutor ling rivalry (males: M=53.13; females: 56). effect’, whereby the elder sibling helps to Twenty-two participants had a same-sex sib- teach the younger sibling. This may mean ling, and twenty-four participants had a dif- that as the siblings grow up, the elder sibling ferent-sex sibling; however, this appeared to has usually been more conscientious towards make no significant difference on feelings of the younger sibling in terms of education academic sibling rivalry: t=1.38, df=44; p>.05. and therefore feels less academically threat- Descriptive statistics were generated and ened. showed that the only real difference was on This study focused on university students the scores for Conscientiousness; firstborns and university is not only a means to obtain- generally scored higher (mean=54.45) than ing a good career, but also plays a role in an lastborns (mean=38.88). The variation of individual’s personal growth and develop- scores was about the same for each condition ment. This study could therefore have impli- (as shown by the standard deviations). The cations at educational and personal levels. initial plan was to use a parametric t-test to Awareness of birth order and links to per- analyse this ‘Conscientiousness’ data, how- sonality and academic sibling rivalry may be ever, it was important to check whether the important for students to better understand data met the parametric assumptions. The themselves and possible feelings of rivalry, visual aids showed no extreme scores and anxiety, stress or even depression. The aca- further analysis for the other two assump- demic sibling rivalry differences identified in tions was conducted. this study between firstborns and lastborns may influence how these individuals behave Discussion educationally. A difference in academic sibling rivalry It has been suggested that sibling rivalry scores between lastborn and firstborn partic- can cause difficulties for families (Sibling ipants was predicted and found. The fact Rivalry Disorder, 2007) ranging from within that lastborns experience more academic family resentment, to serious physical harm rivalry may be explained by Rimm (2002) between siblings. If the highest level of who found that youngest siblings were more rivalry is academic, as McNerney and Usner likely to feel inadequate compared to eldest (2001) suggest, then university may be an siblings. An alternative explanation derives appropriate place to help individuals to from Zajonc and Mullally (1997) who claim understand and overcome their rivalry. How- that firstborns generally present as more ever there is probably little scope in tutorial

Psychology Teaching Review Vol 15 No 1 51 Julia Badger and Peter Reddy work to make lastborns aware of the possible demic sibling rivalry. Recruiting siblings destructive nature of sibling rivalry and to from the same families could validate this offer coping strategies, although the topic work further. This way there could be a may be of interest to university counselling direct comparison between sibling pairs. services. There may be more scope to Further investigation of the relationship include material on sibling rivalry in teach- between academic sibling rivalry and other ing about undergraduate cognitive, social factors influencing academic performance, and emotional development. It is odd that personal development and employability, psychology programmes often fail to relate such as perfectionism, could be undertaken. their teaching to students’ own early adult- There is also scope to locate academic sib- hood development. Academic sibling rivalry ling rivalry within broader currents of litera- could find a place here amongst selected ture concerning the impact of evolutionary material on the development of epistemo- psychology and related concepts, such as sib- logical reasoning and cognition in under- ling rivalry, on metal health, education and graduates, individual differences, psycho- personal development. metrics, developmental tasks, relationship Finally further work is also required on formation, personal development planning the concept of sibling rivalry in order to bet- and approach to study. Enhancing individu- ter define it, understand it and know how to als’ awareness of possible birth order effects measure it. Conceptually it is rooted in evo- on their educational lives, and helping them lutionary psychology yet can also be thought to find methods for dealing with these of as socially constructed and as contributing effects could help individuals to focus on to sociological constructions such as such what they enjoy doing rather than attempt- social stratification (Armando, 2005). Sib- ing to overtake their sibling in status and ling rivalry is also about family and group respect. It could help to reduce the extent to dynamics and further input from psychody- which undergraduates focus on degree namic perspectives may be valuable. It may grade rather than what they are learning. also be fruitfully connected to non-family The results presented here suggest that group contexts where individuals both com- there is an influence of birth order on aca- pete and combine, school classrooms and demic sibling rivalry. However there are still playgrounds and military units for example. a range of variables that could have influ- As demographics change and small or only- enced this finding and need further investi- child families become more common world- gation or control. It would be interesting to wide, it may be useful to consider the investigate whether results would be differ- benefits of sibling rivalry and the implica- ent if only individuals with a similarly aca- tions for other social contexts of the loss of demic sibling were recruited. Future siblings to be in rivalry with. research could also investigate both first and In conclusion previous research sug- last-born siblings from the same family. This gested that birth order could influence vari- would also provide more control over various personality traits such as ables such as upbringing, early schooling Conscientiousness, Openness to Experience and socio-economic status. Another impor- or Agreeableness, as well as playing a part in tant variable to consider is sibling gender; sibling rivalry. However, only a limited extending this work could allow for the con- amount of research had investigated the sideration of all four permutations: sister-sis- influence that birth order could have on ter, brother-brother, brother-sister, and experiencing feelings of academic sibling sister-brother. This would allow for gender- rivalry. Participants in this study did show rivalry investigation and would enable the certain differences concerning personality researchers to see whether one combination traits, although only the difference for Con- of siblings is more likely to experience aca- scientiousness was found to be significant. In

52 Psychology Teaching Review Vol 15 No 1 The effects of birth disorder on personality traits and feelings of academic sibling rivalry addition, this study showed a significant dif- Correspondence ference concerning feelings of academic sib- Julia Badger, Centre for Learning Innova- ling rivalry between firstborns and lastborns. tion and Professional Practice/School of However, whether these differences could Life and Health Sciences, Aston University, have any consequential effect is a question Birmingham, UK. for further research in this area. In summary, E-mail: [email protected] birth order can influence personality traits and academic sibling rivalry, but further investigation is required before wider gener- alisations can be made.

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